Assessing the Effects of a 3-Dimensional (3D) Pathology Tissue-Processing Workflow on Downstream Molecular Analyses.

PURPOSE: Nondestructive 3-dimensional (3D) pathology methods have emerged in recent years with the potential to enhance standard 2-dimensional histopathology by greatly increasing the amount of tissue sampled by imaging and by providing volumetric morphological context. Another key advantage is that tissues remain intact, allowing re-embedding after imaging for potential long-term storage and future histological or molecular analyses. Here, we aimed to systematically evaluate the impact of 3D pathology protocols on biomolecules-including DNA, RNA, and proteins-and their compatibility with downstream assays.

MATERIALS AND

METHODS

We applied a previously optimized 3D pathology protocol-involving deparaffinization, fluorescent hematoxylin and eosin-analog staining, optical clearing, and open-top light-sheet microscopy-to formalin-fixed paraffin-embedded specimens of breast, prostate, and head and neck cancer. Following the protocol, tissues were re-embedded in paraffin and compared with paired formalin-fixed paraffin-embedded controls that did not undergo 3D pathology processing. DNA and RNA were extracted and subjected to quality assessments. Amplifiability was tested by PCR and real-time reverse-transcription quantitative PCR (RT-qPCR) of housekeeping genes.

RESULTS

A slight decrease in the average yield and increased fragmentation of both DNA and RNA were observed in the 3D pathology-processed group compared with the control, but PCR amplifiability was largely preserved. Sanger sequencing of the PCR products confirmed accurate sequence determinations, whereas total RNA sequencing indicated that the global transcriptomic profile was largely unchanged. Immunohistochemistry staining of common biomarkers produced comparable signals, suggesting preservation of those proteins after the 3D pathology workflow.

CONCLUSIONS

These results demonstrate the basic feasibility of combining 3D pathology with downstream molecular analysis, justifying future work to further explore the integration of 3D pathology with diverse advanced molecular assays.